1. Field of the Invention
The present invention relates to laser systems, particularly aircraft laser systems wherein the laser beam is transmitted externally to a turret mounted to the aircraft, the turret in turn receiving and directing the beam to a target.
2. Description of the Prior Art
The conventional laser system utilizes a laser beam generating device and a pointer/tracker for tracking the target and then directing the laser beam to the target. Pointer/tracker field-of-regard (field-of-regard in the context of the present invention means the solid angle the tracker and target beams can scan without interference with the aircraft structure) requirements typically result in the need to place the pointer/tracker at the extremity of the aircraft, with the beam relayed from a remotely located laser generating device by an optical relay train. In an aircraft, for example, the pointer/tracker is typically mounted in the nose and the laser beam is coupled to the pointer/tracker though an optical relay train which is typically housed in a conditioned tube having a diameter larger than the laser beam and configured to route the beam around structural and equipment obstacles, the approach generally being compatible with all types of fuselage installations. Aircraft wings, and horizontal and vertical tail surfaces, on the other hand, are not as readily usable especially for fighter type aircraft. The reasons for this are that the wing thickness is frequently about the same as the beam tube diameter, especially near the wing tips and the trailing edges of the wing. Thus, wing deflections could prevent the use of a simple point-to-point beam tube since the laser beam could possibly interfere at the wing surface. More complicated optical paths using short beam tube segments may incur unwanted losses at each relay mirror and also require auto-alignment at each mirror position. Other alternatives, such as fiber-optic waveguides, are not suitable for high energy densities due to optical losses, thermal problems and weight. Although thicker or stiffer wing sections may be utilized, these alternatives are not always appropriate for a given aircraft design. Further, optical relay through a wing is frequently impractical due to the presence of landing gear, fuel tanks, actuators and other such elements that require multiple blends in the beam tube.
The pointer/tracker optics are typically mounted in a rotatable device, or turret, which can be incorporated as part of the aircraft as noted hereinabove. In accordance with the above discussion of the existing state of the art, the only alternative to a nose installation is to mount the turret on other areas of the aircraft fuselage. However, the field-of-regard available to the fuselage mounted system can be severely limited by fuselage itself as well as by other elements such as wings and tail surfaces. Therefore, a pointer tracker mounted to the nose would have its field-of-regard limited by both the shape and size of the aft fuselage. Further if the pointer/tracker is mounted on the rear of the fuselage, both the aircraft tail components and engine exhaust could interfere with the field-of-regard.
It has been determined that the field-of-regard available to an aircraft laser system would be greatly increased if the turret could be remotely mounted to a wing pod, for example. An aircraft laser system that would enable a turret to be mounted to the wing-tip, or pod, while avoiding the problem mentioned hereinabove would thus be desirable.